Hi nerds! I expect you enjoyed watching my last video. You’re welcome. I’ll reward you with another video. Today. I am further discussing the block diagram of the PIC16F684. It’s really important that you subscribe. So, go ahead and do that. Now, please! Alright, so let’s take a look at the PIC16F684 block diagram. In the PIC16F684 microcontroller, the program bus is an internal pathway used to transfer program instructions and data between different components within the microcontroller. Specifically, it connects the program memory (where the program instructions are stored) to the CPU (Central Processing Unit). Here's a breakdown of its role: Fetching Instructions: The program bus is used by the CPU to fetch instructions from the program memory. These instructions are stored in the program memory as a sequence of binary codes. Instruction Execution: Once an instruction is fetched, the CPU decodes and executes it. This process may involve reading or writing data to/from other parts of the microcontroller, such as the data memory or I/O ports. Addressing: The program counter (PC) in the CPU holds the address of the next instruction to be fetched from the program memory. This address is sent over the program bus to access the correct memory location. Transfer of Data: In addition to fetching instructions, the program bus may also be involved in transferring data that is part of the program instructions, such as immediate values or addresses for branching operations. In the block diagram of the PIC16F684, the program bus is typically depicted as a set of lines connecting the program memory to the CPU, indicating the flow of instruction codes from the memory to the CPU for execution. This bus is crucial for the operation of the microcontroller, as it ensures the proper sequence and execution of the stored program. Alright, let’s talk about what the "Instruction Reg" is. You can see the “instruction red” shown in the PIC16F684 block diagram. The "Instruction Reg" (Instruction Register) shown in the PIC16F684 block diagram is a critical component in the microcontroller's CPU. Its primary function is to temporarily hold the current instruction fetched from the program memory before it is decoded and executed by the CPU. Here's a detailed explanation of its role: Fetching: The instruction register receives the instruction from the program memory via the program bus. This instruction is fetched based on the address specified by the program counter (PC). Holding: Once the instruction is fetched, it is stored in the instruction register. This temporary holding allows the CPU to decode and execute the instruction while the next instruction is being fetched from the program memory. Decoding: The instruction register contents are decoded by the instruction decoder, which interprets the binary code of the instruction to determine the required operation. Executing: After decoding, the CPU executes the instruction. This may involve various operations such as arithmetic calculations, data transfer, logic operations, or control operations. In summary, the Instruction Register in the PIC16F684 block diagram is essential for holding and processing each instruction fetched from the program memory, enabling the CPU to perform its tasks sequentially and efficiently. Basically, the “instruction register” is a thing. It holds the instruction for processing. Next, as you were looking at the PIC16F684 block diagram, you may have asked yourself, what is the "addr mux"? I’m glad you asked, because I have an answer. You’re welcome. In the PIC16F684 microcontroller, the "addr mux" refers to the address multiplexer. This component plays a crucial role in managing the addresses sent to the program memory and other memory components within the microcontroller. Here’s a detailed explanation of its function: Address Selection: The address multiplexer (addr mux) selects between different sources of addresses that need to be sent to the program memory or other memory components. These sources typically include the program counter (PC), which provides the address of the next instruction to be fetched, and potentially other address sources for special operations like interrupts or jumps. Program Counter (PC): The addr mux typically selects the address from the program counter during the normal execution flow, allowing the sequential fetching of instructions from the program memory. Interrupts and Jumps: When an interrupt occurs or a jump instruction is executed, the addr mux switches to select the new address provided by the interrupt vector or jump instruction, redirecting the execution flow to the appropriate memory location. Efficiency and Control: By using an addr mux, the microcontroller efficiently manages the flow of instruction addresses, ensuring that the correct instruction is fetched at the right time. This is crucial for the microcontroller’s operation, particularly in handling sequential execution, branching, and interrupts. In summary, the "addr mux" in the PIC16F684 block diagram is an address multiplexer that selects the appropriate address source (usually between the program counter and other sources) to access the correct memory location, enabling proper instruction fetching and execution. Alright, I am going to end this video here for now. I want to continue to examine the PIC16F684 block diagram. However, to fully explain my next topic, it requires an explanation of indirect addressing. I’ll cover than in my next video. Thanks for watching. Stay tuned. And, please subscribe.
